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Prof. Sáez-Chillón Gómez, Diego25/05/2026, 11:40
The reconstruction of the images of the supermassive objects at the centres of the M87 and Milky Way galaxies show two objects characterized by a central depression in luminosity (the so-called shadow) and a ring-shaped light structure around them. Both properties are closely linked to the emission intensity profile of the accretion disk and to the structure of spacetime. In addition, the...
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Ruchika, Ruchika (University of Salamanca)
As next-generation telescopes and observational surveys continue to expand the boundaries of our understanding, tensions and discrepancies between observational datasets are becoming increasingly prominent. In this work, we focus on one such discrepancy: the differences between 2D and 3D Baryon Acoustic Oscillation (BAO) measurements. Without extending beyond the standard $\Lambda$CDM...
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Marañón González, Francisco Javier (Universidad de Valencia - IFIC)
We present a closed-form framework for the renormalized stress-energy tensor of a scalar quantum field in arbitrary $3+1$-dimensional curved spacetimes through a reformulation of the Hadamard scheme. This approach allows one to construct explicit expressions bypassing the standard mode-sum procedure and rendering the semiclassical field equations more tractable. As an application, we construct...
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Silva, Francisco (Faculdade de Ciências da Universidade de Lisboa)
In this talk, we investigate the horizon structure of accelerating black holes described by the C-metric, including its superaccelerating limit. We then analyze the stability of the Cauchy horizon in these configurations using Christodoulou’s formulation of Strong Cosmic Censorship.
To this end, we classify the families of quasinormal modes of the spacetime and study their properties for...
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Mr Peñalver Mares, Daniel (Universitat de València - IFIC)
In the context of Hawking-like radiation in sonic black holes formed by BECs we investigate the modifications of the emission spectrum caused by a finite width of the sonic transition region connecting the subsonic to supersonic flow [1].
Acoustic black holes formed by Bose-Einstein condensates (BEC) undergoing transonic motion have shown the presence of Hawking-like radiation [2,3,4]. The...
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Giorgi, Giacomo (Universidad de Murcia)
In this talk, I will give a brief introduction to p-brane Aristotelian geometry, the underlying geometry of physical models without boost symmetry, and take the first steps in constructing matter-coupled Aristotelian gravity theories through a conformal approach. I will distinguish between three cases of Aristotelian gravity: electric, magnetic, and electric-magnetic, and then discuss how to...
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Pnigouras, Pantelis (University of Alicante)
During the late stages of a neutron star binary inspiral finite-size effects come into play, with the tidal deformability of the supranuclear density matter leaving an imprint on the gravitational-wave signal. As demonstrated in the case of GW170817—the first direct detection of gravitational waves from a neutron star binary—this can lead to constraints on the neutron star equation of state....
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Pravda, Vojtech (Institute of Mathematics of the Czech Academy of Sciences)
We study static, spherically symmetric, asymptotically flat and asymptotically (A)dS charged black holes in quadratic gravity. Using the conformal-to-Kundt method, we simplify the field equations and derive the solutions in the form of a power series with coefficients determined by a recurrent formula. In addition to charge and mass, these black holes possess one additional parameter – the...
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del Rio, Adrian (Universidad Carlos III de Madrid)
Maxwell's equations in vacuum exhibit a duality invariance under electric-magnetic rotations. This is a Noether symmetry of the source-free Maxwell theory in any curved spacetime, and implies that the circular polarization state (the Stokes V parameter) of classical electromagnetic waves is conserved during propagation, even in the presence of strong gravitational fields.
Remarkably,...
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Aranguren, Eneko (University of the Basque Country (EHU))
Static and spherically symmetric isotropic compact stars are known to exist and be unique for a given monotonic equation of state E(P) and central pressure Pc, provided that Λ ≤ 0, or 0 < Λ < κE(r)/2 holds inside the star. In this work, we extend these results in two directions. First, we relax the standard condition for monotonicity and smoothness of E(P), and generalize the formalism for...
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Castells, Lucía (University of Barcelona)
We perform a detailed holographic analysis of linear fluctuations in a strongly coupled plasma subject to a first-order phase transition. This analysis is done through the characterization of the energy-momentum tensor correlation functions across the phase diagram. Particular attention is given to the behavior of modes near the spinodal region of the phase transition, where the instability...
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Papajčík, Matúš (Charles University)
Gravitational fields are typically described in terms of local curvature, but the physical interpretation of curvature is not immediately evident. This motivates the study of the motion of test particles, whose relative acceleration is governed, in the simplest approximation, by the equation of geodesic deviation.
In this talk, we apply this concept within topologically massive gravity, a...
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Prof. Santos, JOAO (UFCG, Leibniz University and University of Heidelberg)
The Fast Radio Bursts (FRBs) are some of the most intriguing radio phenomena measured in radio astronomy \cite{lorimer}. These energetic bursts have extremely high radio luminosities, corresponding to $\sim 10^{36} \,–\, 10^{44}$ $\mathrm{erg \,s}^{-1}$, which is not far from gamma ray bursts. Since their discovery in 2007, several investigations have been proposed to model their sources and...
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Ossowski, Maciej (Jagiellonian University)
Isolated horizons provide a local generalization of black hole horizons that does not require the existence of a global symmetry and admits matter content arbitrarily close to the surface. Remarkably, in General Relativity, the geometries of Petrov Type D and extremal isolated horizons are governed by equations stated on a 2D local section of the horizon, namely the Petrov type D Equation and...
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Laporte, Cristóbal (University of Barcelona)
Quantum gravity corrections at the classical level are typically expected to be negligible. In this talk, I will present a mechanism by which even parametrically small corrections to the Schwarzschild solution, Planck-suppressed at asymptotic scales, become dominant in the near-horizon region. By analyzing linear perturbations around the Schwarzschild background, we find that higher-derivative...
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Belkhadria, Zakaria (Université de Genève & Università di Cagliari)
Spontaneous scalarization is a mechanism that allows black holes to develop a non-trivial profile of a scalar field “scalar hair” because of tachyonic instabilities, enabling tests of gravity beyond General Relativity. Motivated by stability and threshold issues in Gauss-Bonnet scalarization, we propose a new model characterized by two nonminimal couplings of the scalar field to both...
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Kanatchikov, I (Natl. Quantum Information Center in Gdansk, Poland)
We show that a variety of non-Keplerian galaxy rotation curves, together with the corresponding modifications of the Newtonian potential and dynamics, including MOND, qMOND, and mMOND-type behaviors, can be derived for test particles propagating on a background quantum geometry associated with a fluctuating spin connection, as described by precanonical quantum gravity (pQG).
In particular,...
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Pereñíguez Rodríguez, David
At high frequencies, the dynamics of black holes can be captured by Penrose-limit plane waves adapted to the photon ring. Using that, I will show that gravitational electric–magnetic duality is restored on-shell in that limit, and that this implies QNM isospectrality. I will also show how this perspective on the high-frequency regime can be used to compute exactly nonlinear QNM solutions. I...
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Ogurol, Leyla
We analytically construct initial data for binary black hole systems by solving the Einstein con-
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straint equations within the Bowen–York framework. Allowing for arbitrarily oriented linear mo-
menta and spins, we obtain a perturbative solution of the vacuum Hamiltonian constraint up to third
order in the source parameters. Our solution explicitly incorporates the binary nature of the... -
Málek, Tomáš
We present a classification of four-dimensional gravitational theories exhibiting integrability properties similar to quasi-topological gravity, focusing on metrics that share the symmetries of Schwarzschild and Taub–NUT solutions with spherical, hyperbolic, and planar horizons, as well as their double Wick–rotated counterparts, including B-metrics, the near-horizon extremal Kerr geometry, and...
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Moura, Filipe (ISCTE - Instituto Universitário de Lisboa)
We show that the quasinormal modes, in the eikonal limit, for accelerating (non-rotating) black holes, are related to the angular velocity of the circular null geodesics and to the corresponding Lyapunov exponent, in the same way as the ones for spherically symmetric black holes are. We compute those quasinormal modes and greybody factors for neutral and charged accelerating black holes,...
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Murcia, Ángel (Instituto de Física Teórica)
The celebrated works by Penrose and Hawking established that black holes in general relativity are inevitably doomed to contain singularities in their interiors. This is no longer the case for regular black holes, for which no singularities appear. Recently, it has been shown that the Schwarzschild singularity may be resolved after the addition of an infinite tower of higher-curvature...
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de Cesare, Marco (Scuola Superiore Meridionale (SSM))
I will discuss the scattering problem for a massless scalar field in a Schwarzschild-de Sitter geometry. A rigorous application of the method of matched asymptotic expansions allows us to solve analytically the low-frequency s-wave dynamics, and connect the scalar’s evolution in the proximity of the black-hole horizon with that on cosmological scales. The scattering coefficients, greybody...
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Del Piano, Manuel (Southern Denmark University)
We investigate the backreaction of a massive scalar configuration (“wig”) on a Schwarzschild black hole within a controlled perturbative framework. Working in ingoing Eddington–Finkelstein coordinates, we adopt the test-field approximation and solve the Einstein equations consistently to leading nontrivial order in the scalar stress-energy tensor. The scalar sector is treated using Detweiler’s...
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Musso, Marcello
Inferring abundance, position and size of cosmic structures from the initial conditions is a long standing effort in theoretical cosmology.
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It allows (semi-)analytical predictions of mass function, bias and correlation functions of dark matter haloes, and an intuitive understanding of the formation of the cosmic web, a complementary tool to numerical simulations. Standard methods assume that... -
Wagle, Pratik (Max Planck Institute for Gravitational Physics)
Gravitational-wave observations provide a powerful probe of gravity in the strong-field regime, particularly through the ringdown phase of binary black hole mergers, where the signal is governed by damped quasinormal modes. Recent progress has extended quasinormal-mode calculations beyond general relativity using the modified Teukolsky formalism and spectral methods in several theories,...
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Singha, Chiranjeeb
In this talk, I will first discuss the tidal response of rotating BTZ black holes to scalar perturbations, showing that the real part of the response function is non-zero and therefore leads to finite tidal Love numbers (TLNs). The response also exhibits scale-dependent logarithmic running. Extremal rotating BTZ black holes show qualitatively similar behaviour, and I will outline a procedure...
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Cocco, Marta (University of Perugia and Niels Bohr Institute)
Tidal interactions can significantly impact the dynamics of binary systems and their gravitational-wave signals. In particular, for extreme-mass-ratio inspirals (EMRIs), a fully relativistic description is required to capture the interplay between spin, curvature, and orbital dynamics in the strong-field regime.
We study the response of a Kerr black hole to external tidal fields and its...
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Contreras, Ernesto (Universidad de Alicante)
Regular black holes provide a compelling framework to address spacetime singularities through nonlinear electrodynamics, yielding geometries that remain well-behaved at all scales. In this work, we investigate their response to scalar field perturbations and the onset of spontaneous scalarization. Using a general inverse approach, we reconstruct the electromagnetic sector associated with a...
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